This invention relates to an apparatus for removing foreign material from a rapidly rotating fiber opening roll of a fiber processing machine which may form part of a fiber processing line. The clothing of the opening roll is associated with at least one feed roll (also referred to hereafter as withdrawing roll), a cover and an optical sensor system for recognizing foreign material. The optical sensor system is connected with an electric control-and-regulating device which, in turn, is coupled to a device which removes the foreign material and which includes a mechanism for generating an air blast directed to the clothing of the opening roll for dislodging and carrying away the foreign material from the clothing of the opening roll.
German Offenlegungsschrift (application published without examination) No. 195 43 526 discloses an apparatus in which two slowly rotating feed rolls laterally cooperate with the opening roll for advancing the fiber material thereto. Guide plates are provided for maintaining the co-rotating air screen on the opening roll. At the lower end of the opening roll a sensor device is disposed for optically recognizing foreign bodies in the fiber tufts. The sensor device is disposed in a collecting chamber for the separated foreign parts. Between the guide plate and a knife an aperture is provided through which, for a short period of time, an air blast is directed from below in an oblique orientation to that region of the roll surface where the fiber tufts contain the foreign bodies. As a result, the contaminated fiber tufts are blown off the roll surface and are subsequently carried away.
It is a disadvantage of the above-outlined prior art device that it needs substantial space because of the lateral introduction of the fiber tufts from a laterally arranged accumulator, conveyor or the like and also because of the arrangement of the optical sensor device and the blowing direction of the air-blast generating source in the region underneath the opening roll. It is a particular drawback that the air-blast generating device is situated in the waste collecting chamber which may lead to significant operational disturbances, interruptions and down times.